Apparatus for handling flexible containers for liquid sample spectrometry

ABSTRACT

Flexible sample containers for liquid scintillation spectrometry analysis of test samples containing one or more radioactive isotopes disposed in a liquid scintillator wherein the flexible sample containers either in individual or strip form are made of layered, flexible, light-transmissive, polyester film and are provided further with means for avoiding light &#39;&#39;&#39;&#39;piping&#39;&#39;&#39;&#39; or optical isolation from respective adjacent sample containers. Apparatus for handling such flexible sample containers is provided with light transmission sealing means for preventing entry of ambient light or escape of light from the photomultiplier tube detection devices. Also disclosed are methods and apparatus for filling, forming, sealing and handling the aforementioned flexible sample containers that readily lends itself to fully automated production line type operations.

United States Patent Frank Dec. 2, 1975 APPARATUS FOR HANDLING FLEXIBLE CONTAINERS FOR LIQUID SAMPLE SPECTROMETRY [75] Inventor: Edmund Frank, Chicago, Ill.

[73] Assignee: Packard Instrument Company, Inc.,

Downers Grove, Ill.

22 Filed: Dec. 28, 1973 21 App]. No.: 429,074

Related U.S. Application Data [62] Division of Ser. No. 259,767, June 5, 1972.

Primary Examiner-James W. Lawrence Assistant ExaminerDavis L. Willis Attorney, Agent, or Firm-Wolfe, Hubbard, Leydig. Voit & Osann, Ltd.

[57] ABSTRACT Flexible sample containers for liquid scintillation spectrometry analysis of test samples containing one or more radioactive isotopes disposed in a liquid scintillator wherein the flexible sample containers either in individual or strip form are made of layered, flexible, light-transmissive, polyester film and are provided further with meansfor avoiding light piping" or optical isolation from respective adjacent sample containers. Apparatus for handling such flexible sample containers is provided with light transmission sealing means for preventing entry of ambient light or escape of light from the photomultiplier tube detection devices. Also disclosed are methods and apparatus for filling, forming, sealing and handling the aforementioned flexible sample containers that readily lends itself to fully automated production line type operations.

9 Claims, 34 Drawing Figures Sheet 2 0f 8 3,924,128

US, Patent Dec. 2, 1975 Sheet 4 of 8 .,S;.. Patent Dec. 2, 1975 US, atenit Dec. 2, 1975 Sheet 5 of8 3,924,128

UQS. Patfint Dec. 2, 1975 Sheet 7 of8 3,924,128

US. Patent Dec. 2, 1975 Sheet 8 of 8 3,924,128

APPARATUS FOR HANDLING FLEXIBLE CONTAINERS FOR LIQUID SAMPLE SPECTROMETRY This is a division of application Ser. No. 259,767 filed June 5, 1972.

DESCRIPTION OF THE INVENTION This invention relates generally to apparatus for han-v dling flexible sample containers in liquid scintillation spectral analysis of test samples containing one or more radioactive isotopes disposed in a liquid scintillator. More particularly, the invention relates toimproved handling arrangements for such flexible sample con,- tainers in individualor strip form and which readily lend themselves to fully automatic operations.

BACKGROUND AND-OBJECTS Flexible sample containers for liquid scintillation spectral analysis of test samples containing one or more radioactive isotopes disposed in a liquid scintillator and methods and apparatus for handling the same are described and claimed in the copending application of Lyle E. Packard and Ariel G. Schrodt, Ser. No. 192,543 filed Oct. 2, 1971 and assigned to ,the assignee of the present invention. Such flexible containers comprise a flexible bag formed in layered polyester filmswhich are heat sealed, welded or otherwise joined to define a closed flask between the layers. The aforesaid copending application of L. E. Packard et al further describes and claims methods and apparatus for utilizing such flexible containers for liquid scintillation detection operations in a wholly automated manner.

It is therefore, the general object of this invention to provide improved mechanisms for handling such containers for spectral analysis of test samples confined DESCRIPTION OF DRAWINGS Other objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front sectional view of an exemplary radioactive sample handling and measuring apparatus, housed in a suitable cabinet and depicting the handling of flexible containers in accordance with the present invention;

FIG. 2 is an enlarged fragmentary view taken of the counting station of the apparatus in FIG. 1 illustrating light piping prevention means in the form of annular seals associated with the photomultiplier tubes and here showing the tubes brought into contact with the container in the counting station;

FIG. 3 is a diagramatic illustration of an exemplary arrangement for preparation of acontinuous strip of flexible sample containers;

FIG. 4 is an enlarged perspective view of a portion of a strip of'containersshownin FIG.3, here depicting one form of light piping prevention barrier between the container portions of the strip;

FIG. 5 is an enlarged, fragmentary top plan view of the flexible containers-of FIG. 4;. l

FIG. 6 is a perspective view showing a portion of a strip of another form-offlexible containers;

FIG. 7 is a view taken alongthe line 7-7 in FIG. 6; FIG. 8 is a diagramaticillustration of an arrangement for producing the flexible con'tainers of FIGS. 6 and 7; I FIG. 9 is a-viewin perspective of yet another strip of flexible containers;

FIG. 11 is a view in perspective of yet another strip form of flexible containers adapted to be closed with crimp clips; I 7 I I FIG. 12 is a t'ransverse sectional view'taken along the line 12-12 in FIG. 11 and here depicting a crimp clip in sealing position; I

. a container of FIG. 13 sealedwith a clip;

.FIG. 15 is a view in perspective of an individual flexible sample container shown in a rigid mount and depicting the.folding that takes place to complete the mount; FIG. 16 is an exploded view in perspective of an individual form of flexible container and reflection .rings provided therefor; I

.FIGrl7 is a view of the container FIG. 16 with the rings in place; 1 FIG. 18 is a fragmentary diagramatic view showing the flexible sample containers of FIGS. 16 and 17 disposed between a pair of photomultiplier tubes;

FIG. 19 is a view in perspective of yet anotherform of flexible. container construction having rigid support means integrally formed therewith;

FIG. 20 is an exploded view of the components of the flexible container of FIG. 19; FIG. 21 is a edge view of the flexible container of FIG. 19; e

FIG-:22 is a perspective view of yet another form of flexible container with rigid support disposed between a pair of sheets;

FIG. 23 .isan exploded view of thecontainer of FIG. 22; i

FIG. 24 is aview taken along the line 24--24 in FIG.

22; I r e FIG. 25 isa diagramatic view illustrating the process sequence of making, filling andstackingindividual flexible containers embodying features of the present invention; V

' FIG. 26 is a fragmentaryview of the filling station of FIG. 23, here depicting the injection means for inserting samples into the-container; t

FIG. 27 is a diagramatic representation of an alternative form of-detector apparatus adapted to handle individual. flexible sample containers;

- FIG. 28 is a view in perspective of a detector module,

showing the shutter operating mechanism and sample container elevator;

FIG. 29 is an enlarged fragmentary view, partly in section. showing the details of an axially shiftable photomultiplier tube mounting; I

FIGS. 30, 31 and 32 are diagramatic representations, respectively, of a cycle of operation of the shutters and elevator for an exemplary detection apparatus; and

FIGS. 33 and 34 are alternative arrangements for shuttering containers into a counting station while sealing against entry of ambient light.

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of examples in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

GENERAL APPARATUS ARRANGEMENT Referring to FIG. 1, there is illustrated a liquid scintillation apparatus, indicated generally at 40, which houses a scintillation detector mechanism or apparatus 42. The detection apparatus of FIG. 1 is detailed in the aforementioned copending application of Lyle E. Packard and Ariel G. Schrodt, Ser. No. 192,543 filed Oct. 2, 1971. In brief, the detection apparatus 42 as viewed in FIG. 1, includes a base assembly 44 which houses a pair of photomultipliers PMT No. 1, PMT No. 2 disposed on opposite sides of a counting station 46.

The photomultipliers PMT No. l, PMT No. 2 are preferably mounted so as to permit controlled simultaneous movement toward and away from the counting station 46. To this end, in the present exemplary arrangement the photomultiplier tubes are slidably carried in tubular guides 48 with ball bearing mounts 50. Light-tight bellows 52 intereconnect the guides 48 with the photomultiplier tube sockets 54. The bellows contain compression springs 56 to normally bias the tubes outwardly from the counting station 46.

In order to effect the controlled simultaneous movement of the photomultiplier tubes toward one another along a common axis, there is provided a pair of cams 58, 60 acting respectively upon the sockets 54 of photomultiplier tubes PMT No. l and PMT No. 2. A suitable actuating mechanism (not shown) rotates the cams 58, 60 to act upon the sockets and drive the photomultiplier tubes toward each other which, as more fully discussed below, permits close optical coupling with sample containers in the counting station 46.

FLEXIBLE CONTAINER ARRANGEMENT As shown in conjunction with FIG. 1, the sample containers utilized with the apparatus 40 are in the form of a continuous strip 62 of flexible bags 64. For details of the flexible sample container construction, reference is made to the aforementioned copending L. E. Packard et al application Ser. No. 192,543. For the purposes of this application it should suffice to say that the flexible sample containers 64 are produced from layered lighttransmissive polyester film strips which are heat sealed, welded or otherwise suitably joined to define a closed flask-like portion between the layers. The flask-like portion has provision for injecting test samples into the closed chamber therein and is sealable to confine the sample in the bag portion without leakage.

In its preferred form, the bag is circular in the plane of the layers with a diameter closely approximating the diameters of the photomultiplier tubes so that there is conformity with the round photomultiplier tubes to provide the optimum counting geometry for the container structure.

FLEXIBLE CONTAINER TRANSFERENCE AND HANDLING With the provision of a continuous strip of flexible containers, compact storage on a reel 66 (FIG. 1) is possible and the transference of the sample through the detector apparatus involves a passing of the strip from reel 66 to reel 68, the latter being shown as manually operated through crank handle 70. During the time when the containers are being shifted into and out from the counting station 46, the photomultiplier tubes PMT No. 1 and PMT No. 2 are in the retracted, axially spaced apart position. When the particular container 64 holding the test sample to be analyzed is in the counting station, the photomultiplier tubes are then moved axially together until they are in intimate contact with the outer faces of the container (FIG. 2).

The photomultiplier tubes are brought together with sufficient pressure so as to squeeze the flexible container therebetween causing the outer walls of the container to conform with the faces of the photomultiplier tubes. With this arrangement, an extremely close optical coupling results which minimizes lost light at the contact surfaces of the container and tubes and maximizes quantitative accuracy of liquid scintillation counting results.

OPTICAL ISOLATION In accordance with one of the aspects of the present invention, provision is made in respect of the apparatus and the flexible sample container bags or both to avoid lightpiping (transmission of light through the film material) and to provide optical isolation from sample containers adjacent to the containers in the counting station. To this end, the photomultiplier tube guides 48 are provided with flanged ended portions 72 to which there is mounted soft annular sealing rings 74 which coaxia'lly contact opposite sides of the interconnecting strips or borders between the container bags. The sealing rings exclude outside light from entering the detecfor counting station when the tubes are in the axially together position as shown in FIG. 2, in addition to confining light generated with the photomultiplier tubes from passing into the sample storage enclosures on either side of the counting station.

Elimination or reduction to tolerable minimums of light piping through the interconnecting strip material of the containers is accomplished by the provision of light piping prevention means formed on the container strip web or border which may act in cooperation with the soft sealing rings. To this end, referring to FIGS. 4 and 5, conjointly, there is illustrated one form of light piping prevention means which comprises an embossed area 76 on web 62 between respective adjacent sample containers 64.

The embossment 76, which may be achieved by conventional embossing rolls or dies provides a zig-zag, non-planar path that prevents light from being transmitted directly through the web into adjacent sample containers by portions of the continuous strip. The soft annular sealing rings, discussed. above, in connection with the photomultiplier tube sleeves will conform themselves with the raised and indented portions of the embossments to provide a more effective seal against entry or loss of light.

(A) FABRICATION OF BI-LAYERED CONTAINERS In order to generate a continuous strip of sample containers of the type described above, a system such as that illustrated in FIG. 3 may be utilized. The arrangement is such that a pair of rolls 78 of wound polyester film strip supply the strips as they are unwound. The strips 80, 81 are flattened against each other as they pass through gathering rolls 82, 83 before passing into the heat sealing and embossing apparatus 84.

The exemplary heat sealing and embossing apparatus 84 is shown in the form of a pair of cooperating heated dies 85, 86, the latter of which is shiftable by a servo mechanism 87 or the like to clamp the film strip layers between the dies for simultaneously effecting the heat sealing and embossing operations. Controlled intermittent movement of the film strips and actuation of the heat sealing apparatus produces a plurality of the flaskshaped containers 64 separated by embossments 76 and the strip of containers is then wound into a roll 88 for compact storage in readiness to be filled with test samples.

(B) MULTI-LAYERED CONTAINERS Referring now to FIG. 6, there is shown a slightly modified form of flexible container arrangement for handling liquid samples for scintillation spectrometry wherein instead of two film layers being provided, the container strip is formed from three layers. The layers include a pair of outer transparent or light transmissive layers 90, 91 bonded or sealed to an inner opaque layer 92 (FIG. 7). The flask or bag portion 91 defining the sample containers is formed from a cut-out in the central opaque strip such as that defined by the centrally disposed circular cut-out 95 and the filling opening cutout 94.

The surface area of the outer strips surrounding the defined container portions 91 being heat sealed or bonded to the inner opaque strip are left with a roughened surface 96 which renders them opaque to prevent light piping between the sample container bag through interconnecting material of the strip.

(C) FABRICATION OF MULTI-LAYERED CONTAINERS Referring to FIG. 8, there is shown exemplary forming system arrangement for producingthe continuous flexible container strip of FIGS. 6 and 7. As shown in FIG. 8, the opaque strip 92 is moved intermittently along a straight path from a source (not shown) to a take up shaft 93. During its movement, the strip 92 first passes through a punch 98 which cuts out the key-hole shaped opening 100 at predetermined spaced intervals along the strip. Next, the strip 92 is sandwiched between strips 90, 91 supplied from rolls 101, 102, respectively prior to passing between gathering rollers 104. The tri-layered strip after emergence from the gathering rolls passes through a sealing and cutting apparatus 105 which joins the outer strips 90, 91 to the opaque strip 92 and trims the top border leaving a neck-like opening in the flasks.

(D) ALTERNATIVE OPTICAL ISOLATION ARRANGEMENTS Turning now to FIG. 9, there is illustrated another form of light transmission or light piping prevention means for the flexible sample container arrangements similar to those shown in FIG. 4 and FIG. 6. In the present instance, the sample containers are again in the form of flexible bags made up of layered, lighttransmissive polyester film joined to define closed flasks between the layers, The top and bottom borders 109, are opaque through the provision of embossments, metallized strips, or magnetizable strips such as that described .in copending application Ser. No. 192,543.

In order to prevent light transmission through the layered film borders on opposite sides of the sample bag portion, elongated transverse slots 112 are formed in the layered borders adjacent to the bags 108. The slots 112 provide discontinuities in. the path of light travel through the film layers.

A still further modification is illustrated in FIG. 10 where instead of one slot, there is provided a plurality of rows of spaced slots 114. The slots of each row are staggered with respect to the slots of an adjacent row or rows so that a straight path of travel for light is avoided. The slots also add more flexibility to the strip for handling and storage in a rolled form.

(E) CONTAINER SEALING Referring now to FIG. 11, there is illustrated a portion of a continuous strip of flexible sample containers 1 16 having a plurality of flask-shaped bag portions 118 therein and provided with neck filling openings 120. After the bag portions have been filled with the test samples, the neck portions may be heat sealed or otherwise joined to provide a liquid tight seal against escape of the test samples. However, in FIGS. 11 and 12 there is shown an alternative arrangement for sealing the containers which provides an effective seal yet allows the containers to be easily unsealed for removal of the samples therefrom.

To this end, the edge portion 122 of the strip containing the necks is folded over and a crimp clip 124 is clamped over the folded portion overlying the container filling neck. The clip 124 may be made of any suitable material" such as a soft metal which is sufficiently ductile to tightly clamp the bent over film portions of the container with crimping operations or the like.

Referring to FIGS. 13 and 14, conjointly, there is illustrated another form of removable clip adapted to seal the filling neck portion of flexible sample containers such as those indicated at 126 in FIG. 13. In the present instance, portions of the film border material intermediate that containing the neck portions 128 of the containers 126 have been cut away, as indicated generally at 130, so that the neck portions 128 project outwardly from the top edge 132 of the container strip. The clip 134 is formed of a resilient material such as plastic and has a generally U-shape with a corresponding protuberance 136 and socket 138 on the inside of the leg portions thereof. The arrangement is such that when the clip is placed over the protruding neck portion 128 and the protuberance 136 is snapped into the socket 138 it tightly clamps the container neck portion 128 between the protuberance and socket to prevent escape of the liquid sample in the container bag portion.

(F) MOUNTED FLEXIBLE SAMPLE CONTAINER It will be appreciated that the flexible sample containers as discussed above may be handled individually as well as on a continuous strip. Thus, in accordance with another aspect of the present invention, provision may be made for mounting an individual flexible sample container in a rigid frame which offers yet another mode of storing, handling and transporting the containers. In the exemplary arrangement shown in FIG. 15, an individual flexible container 140 is sandwiched between a pair of rigid layers 142, 143 that may be made of a single piece of stock folded over such as indicated at 142. The rigid material may be polyethylene coated cardboard or the like with cut-out openings 144 (only one being shown) to permit the bag portion 140 to protrude through the opening after assembly.

(G) INCREASED LIGHT COLLECTING EFFICIENCY In carrying out another aspect of the present invention provision may be made with respect to the flexible container bag portions for further increasing the light collecting efficiency with the use of the containers. In carrying out this aspect of the invention, annular members 146, 147 or the like of light reflective material are placed about the peripheries of the bag portions 148 (FIGS. 16 and 17). The annular members may be any suitable light reflective material such as aluminized film or opaque white film. In the alternative it will be appreciated that instead of using separate members a reflec tive coating may be applied about the periphery of the bag portion so that the reflective surface is formed in situ.

Referring to FIG. 18, it will be seen that when the sample container of FIG. 17 is disposed between a pair of photomultiplier tubes PMT No. 1, PMT No. 2 the tube faces engage the outer surfaces of the container bag portion and the peripheral portions thereof containing the light reflective members 146 cover the sides of the bag and provide sloped reflective surfaces which serve to reflect light emitted by the photomultiplier tubes back into the liquid sample rather than allowing it to pass out through the side wall of the container.

(H) FORMED CONTAINERS ple container which will carry a still larger volume of test sample but without increasing the lateral dimension of the bag portion, and in accordance with still another aspect of the present invention, the flask portion may be bulge formed in the direction perpendicular to one or both of the film layers.

As illustrated in FIG. 19, sample container 150 includes polyester film layers 151, I52 and a rigid mou'nt .layer 153. A portion of the flask 154 and filling neck 155 are bulge formed in the layer 151 (FIG. 20)and the rigid layer 153 is provided with an opening 158 to permit protrusion of the bulged portion 156 of layer 152 therethrough (FIG. 21).

Referring to FIGS. 22, 23 and 24, conjointly, there is shown another form of molded flexible container arrangement 160 wherein outer layers 161, 162 include bulged flask portions 163 and an intermediate rigid layer 164 is sandwiched between the inner and outer layers 161, 162. The rigid layer 164 disposed between the film layers is provided with a cut-out 165 corresponding in shape to the flask-shaped bulged portions 163 of the outer layer.

FORMING, FILLING AND HANDLING INDIVIDUAL FLEXIBLE SAMPLE CONTAINERS Turning now to FIG. 25, there is illustrated an exemplary system for forming, filling and arranging individual flexible sample containers in a continuous production-like manner. In the system, a pair of polyester film strips supplied from respective sources (not shown) are merged together through the nip of gathering rolls 172 and then passed through a heat sealing forming station 174 which effects the formation of the flask-like containers 178 in the strip. The forming unit 174, for example, includes vacuum forming dies 175, 176 that bulge the container walls outwardly at the same time that the heat seal joint is formed. The layered strip moves intermittently so that each of the operations takes place while the strip is at rest.

After formation, the containers 178 are advanced to a filling station 180 wherein liquid sample from a source 181 is injected into the container with a hollow needle 182. As best shown in FIG. 26, the needle 182 is adapted to penetrate the neck portion of the container 178 and inject the liquid sample through a hollow opening 183. In order to permit air inside the container 178 to escape during filling, the needle is provided with a vent including an opening 184 disposed longitudinally within the needle and an interconnecting transverse outlet port 185 which permits the escaping air to pass to the atmosphere.

In the production line filling station, a pair of reciprocatingly actuated plungers 186, 187 are provided on opposite sides of the container strip and arranged to apply a pressure to the container faces that stiffens the flask portions to allow for penetration of the needle.

Following the filling operation, the filled containers advance to a heat sealing station wherein a heat sealing head 188 tranversely oriented with respect to the neck of the flask shaped container seals the neck as indicated at 190 beneath the opening left by the filling needle.

The filled, sealed, sample containers are then moved to a pressure test station l92'wherein a predetermined compressive pressure load is applied to test for leakage and the ability to withstand pressures which correspond substantially to that of the load applied by the photomultiplier tubes when they compress the flask during counting,

The container strip then moves to a cutting station 194 wherein a cutter 196 severs the layered film between filled flasks to form individual containers 198 which are then placed in proper order in a compartmentalized holding tray 200 or the like.

Turning to FIG. 27, there is illustrated diagramatically a liquid scintillation apparatus, indicated generally at 202, which may be utilized for spectral analysis of the test samples stored in containers 198 held within tray 200. The detection apparatus 202, as that described in connection with FIG; 1 above, includes a pair of axially shiftable photomultiplier tubes PMT No. l, PMT No. 2 disposed on opposite sides of a counting station 204 within a light tight housing 205 (shown in phantom). The loaded tray 200 is inserted within a sealed sample source supply chamber 206 adjacent the input side of the detector and a sealed sample receiving chamber 207 attached to the housing 205 adjacent the output side of the detector holds a tray 208 which is initially empty and receives the sample containers after testing. i

The trays 200 and 208 are mounted so as to move transversely with respect to the axis of the detector counting station so that the supply tray 200 places the sample containers in position for transference to'the counting station and the receiving tray 208 provides an empty space for receipt of the sample container which has been tested.

Instead of passing the sample containers from a tray in the source chamber completely through the detector apparatus to the receiving tray, provision'rnay be made for transferring containers individually to the counting station and returning the container after counting to the tray from which it came. Referring to FIG. 28, there is shown an exemplary detector counting station and transfer arrangement with photomultiplier tubes mounted for axial shifting toward and away from the counting station similar to that described in connection with FIG. 1. For convenience, the corresponding components previously described in connection with FIG.

1 have been indicated by the same reference numerals of the photomultiplier tubes, a top opening 224 for entry of the sample container 225 and a bottoin open ing 226 coupled to a tube or sleeve 227 through which an elevator shaft 228 passes. For details of an elevator operating arrangement and control therefo'r,reference is made to L. E. Packard US. Pat. No. 3,188,468 issued June 8, 1965.

Pursuant to the invention, the counting station housing 220 is provided with a shutter arrangement to permit entry of a sample container while excluding light from the photomultiplier tubes and after the sample has entered the counting station to close off the top opening to exclude ambient light, and then open the side openings permitting entry of the photomultiplier tubes into the counting station.

To this end, a slidable sample entry opening shutter 230 is positioned beneath the sample entry opening 224 and a pair of shutters 232, 233 are positioned adjacent the photomultiplier tube entry openings 222. The entry opening and tube opening shutters are alternately shifted between their open and closed positions by means of a pin and slot leakage arrangement, indicated generally at 234 (FIG. 29). The pin 235 is transversely carried adjacent the periphery of a gear 236 mounted on brackets 237 connected to the box 220. To drive the gear 236, a pinion gear 238 meshed therewith is carried by shaft 240 journaled in the box 220 and rotated from the outside of the box by a reversible motor 242 (FIG. 28).

The shutter 230 includes depending legs 241 with slots 242 therein arranged perpendicular to the axis of pin 235 carried by gear 236. Similarly, the shutters 232 include slots 243 arranged perpendicular to the axis of pin 235. v

In order to more fully understand the operation of the shutter operating mechanism reference is made to FIG; 30 wherein itis'shown in a cycle start" position in that shutter 230 is retracted and elevator 246 is in :its upward position for receipt of the sample container to be counted. Gear 236 is rotated to a position wherein pin-235 enters the slot 242 of top opening shutter 230 depending legs 241. The 'side opening shutters 232 are in-'a closed position to the right as viewed in FIG. 30 so that they cover the photomultiplier tube entry openmgs.

The elevator carrying the sample container (not shown) at this point moves downwardly until the sample container is positioned within the box 220 between the photomultiplier tubes. Gear 236 with pin 235 continues to rotate clockwise through an angle of approximately driving shutter 230 to the right to where it is shown in FIG. 31. At this point the top entry opening is sealed with the container held in position in the counting station by elevator 246. r A

Gear 236 with pin 235 still continues to rotate clockwise with pin 235 entering slots 243 of shutters 232 and after approximately 180 rotation the shutters 232 are moved to the left as shown in FIG. 32 and the photo multipliertubes may then be moved axially toward the container in'the counting station.

After counting has been completed the tubes retract and gear 236 with pin 235 rotate in the opposite or counterclockwise direction first closing shutters 232 and then opening shutter'230 in successive 180 angles of rotation. When shutter 230 has been opened, elevator 246 may then move upwardly and the shutters and elevator are back in the position shown in FIG. 30 in readiness for another cycle.

Turning to FIG. 33, there is shown another modified arrangement for transferring; individual sample containers 250 into a counting station between a pair of axially shiftable photomultiplier tubes PMT No. l, PMT No. 2. In the present instance, there is provided a sliding shuttle bar 252 having a slotted opening 254 therein adapted to receive a sample container. The shuttle has a first sealing ring 256 which may be made of felt or the like fixedly mounted adjacent the end toward the counting station and a second sealing ring 258 which may be slidable with respect to the shuttle so that when the shuttle moves a sample container into the counting station as shown in phantom in FIG. 33, the sealing rings are disposed on opposite sides thereof to prevent entry of ambient light.

As an alternative to the sliding, sealing ring, there is shown in FIG. 34 a pair of resilient rollers 260 which provide a rotatable seal permitting the shuttle to pass between the nips thereof while preventing entry of light to the counting station. The rollers include a shaft-like central portion 262 of a first diameter and end portions 264 of a larger diameter. The central portion rollers are of a length corresponding to the height of the shuttle along the vertical axis as viewed in FIG. 34 while the end portions 264 overlap and engage one another approximately at the middle of the width of the shuttle along the horizontal axis.

l claim:

1. In an apparatus for spectrally analyzing test samples containing one or more radioactive isotopes disposed in a liquid scintillator and adapted to handle flexible sample containers formed by joining layered, flexible light-transmissive, polyester film to define a bag portion therein, light tight housing means including a counting station, at least one photomultiplier detection device in said housing and means, for axially shifting said photomultiplier detection device toward and away from said counting station, the improvement comprising, a resilient member surrounding the end of said photomultiplier detection device adjacent said counting station, said resilient member being disposed to contact the flexible sample container disposed in the counting station and surround the entire periphery of the bag portions thereof when said photomultiplier detection device is axially shifted toward the sample container to its preselected position for counting.

2. Apparatus as claimed in claim 1 including a second photomultiplier tube device in longitudinally spaced apart relationto said other photomultiplier detection device, said second tube having a second resilient member surrounding its end directed toward the counting station, said second resilient member being coaxially disposed with respect to said first photomultiplier device resilient member.

3. In an apparatus for spectrally analyzing test samples containing one or more radioactive isotopes disposed in the liquid scintillator and adapted to handle flexible sample containers formed by joining layered, flexible light-transmissive, polyester film to define a bag portion therein, the combination comprising,

a source of said flexible sample containers,

at least one photomultiplier detection device adjacent a light tight counting station,

means for axially shifting said photomultiplier detection device toward and away from said counting station,

means for transferring said containers from said source means to said counting station, and

means associated with said transfer means and said photomultiplier detection device for sealing said counting station against entry of ambient light when said transfer means brings the flexible container into the counting station.

4. Apparatus as claimed in claim 3 wherein said transfer means comprises a shiftable shuttle, said shuttle having a sample container receiving opening therein and said sealing means comprising sealing rings surrounding said shuttle and relatively movable into sealing position when said shuttle opening carrying the container is in the counting station.

5. Apparatus as claimed in claim 3 wherein said transfer means comprises a shiftable shuttle having an opening therein for receiving said flexible container and said sealing means comprises a pair of cooperating resilient rollers adapted to permit the shuttle to pass between the nip thereof while preventing entry of light to the counting station, said rollers each including a shaftlike central portion of a first diameter, the length of said central portion corresponding to the height of said shuttle along a first axis and end portions on said rollers of a larger diameter, said roller end portions overlapping the shuttle and engaging one another atapproximately the mid-point of the width of the shuttle along a second axis.

6. Apparatus as claimed in claim 3 wherein said light tight counting station includes a generally box-shape enclosure, said photomultiplier detection device being connected to a first wall of said enclosure having an opening therein for movement into the counting station within said enclosure, an entry opening in another wall of said enclosure for said transfer means to carry the flexible container into said counting station within the enclosure and said sealing means comprising a shutter member movable relative to said entry opening to open and close the same.

7. Apparatus as claimed in claim 6 wherein said photomultiplier detection device entry opening in said enclosure includes a shiftable shutter disposed adjacent thereto for opening and closing said latter opening.

8. Apparatus as claimed in claim 7 wherein each of said shutters include a depending slotted portion and means disposed in said enclosure for alternatively engaging the slotted portions of the respective shutters to shift said entry opening shutter to an open position when said photomultiplier detection device entry opening shutter is in a closed position and shift said photomultiplier detection device entry opening shutter to an open position when said container entry opening shutter is in a closed position.

9. Apparatus as claimed in claim 8 wherein said shutter opening means comprises a rotatable disc member having a transverse pin adjacent its periphery. 

1. In an apparatus for spectrally analyzing test samples containing one or more radioactive isotopes disposed in a liquid scintillator and adapted to handle flexible sample containers formed by joining layered, flexible light-transmissive, polyester film to define a bag portion therein, light tight housing means including a counting station, at least one photomultiplier detection device in said housing and means, for axially shifting said photomultiplier detection device toward and away from said counting station, the improvement comprising, a resilient member surrounding the end of said photomultiplier detection device adjacent said counting station, said resilient member being disposed to contact the flexible sample container disposed in the counting station and surround the entire periphery of the bag portions thereof when said photomultiplier detection device is axially shifted toward the sample container to its preselected position for counting.
 2. Apparatus as claimed in claim 1 including a second photomultiplier tube device in longitudinally spaced apart relation to said other photomultiplier detection device, said second tube having a second resilient member surrounding its end directed toward the counting station, said second resilient member being coaxially disposed with respect to said first photomultiplier device resilient member.
 3. In an apparatus for spectrally analyzing test samples containing one or more radioactive isotopes disposed in the liquid scintillator and adapted to handle flexible sample containers formed by joining layered, flexible light-transmissive, polyester film to define a bag portion therein, the combination comprising, a source of said fLexible sample containers, at least one photomultiplier detection device adjacent a light tight counting station, means for axially shifting said photomultiplier detection device toward and away from said counting station, means for transferring said containers from said source means to said counting station, and means associated with said transfer means and said photomultiplier detection device for sealing said counting station against entry of ambient light when said transfer means brings the flexible container into the counting station.
 4. Apparatus as claimed in claim 3 wherein said transfer means comprises a shiftable shuttle, said shuttle having a sample container receiving opening therein and said sealing means comprising sealing rings surrounding said shuttle and relatively movable into sealing position when said shuttle opening carrying the container is in the counting station.
 5. Apparatus as claimed in claim 3 wherein said transfer means comprises a shiftable shuttle having an opening therein for receiving said flexible container and said sealing means comprises a pair of cooperating resilient rollers adapted to permit the shuttle to pass between the nip thereof while preventing entry of light to the counting station, said rollers each including a shaft-like central portion of a first diameter, the length of said central portion corresponding to the height of said shuttle along a first axis and end portions on said rollers of a larger diameter, said roller end portions overlapping the shuttle and engaging one another at approximately the mid-point of the width of the shuttle along a second axis.
 6. Apparatus as claimed in claim 3 wherein said light tight counting station includes a generally box-shape enclosure, said photomultiplier detection device being connected to a first wall of said enclosure having an opening therein for movement into the counting station within said enclosure, an entry opening in another wall of said enclosure for said transfer means to carry the flexible container into said counting station within the enclosure and said sealing means comprising a shutter member movable relative to said entry opening to open and close the same.
 7. Apparatus as claimed in claim 6 wherein said photomultiplier detection device entry opening in said enclosure includes a shiftable shutter disposed adjacent thereto for opening and closing said latter opening.
 8. Apparatus as claimed in claim 7 wherein each of said shutters include a depending slotted portion and means disposed in said enclosure for alternatively engaging the slotted portions of the respective shutters to shift said entry opening shutter to an open position when said photomultiplier detection device entry opening shutter is in a closed position and shift said photomultiplier detection device entry opening shutter to an open position when said container entry opening shutter is in a closed position.
 9. Apparatus as claimed in claim 8 wherein said shutter opening means comprises a rotatable disc member having a transverse pin adjacent its periphery. 